Marine environment is rich in many natural products with applications in different fields. L- asparaginase (L-asparagine amidohydrolase; E.C.3.5.1.1) is a widely distributed enzyme  among terrestrial and marine organisms. it has an anticancer effect and it is used mainly for  treatment of childhood Leukemia along with many other types of cancers. Another application  of this enzyme is the mitigation of the carcinogenic acrylamide in baked and fried foods. A  third application suggested in this article is its use as a food preservative due to its antimicrobial  effect. In this work L- asparaginase purified from marine Pseudomonas otitidis EGY-NIOF- A1, accession number of OQ547301 is tested against Listeria monocytogenes isolated from  Basa Fillet fish, identified and confirmed by using biochemical tests and MICROBACT  Listeria 12L system. Amino acid analysis showed its rich content of Aspartic acid, glutamic  acid, proline and arginine. the high content of these amino acids supports its antimicrobial  effect. Future considerations should be devoted for the use of L- asparaginase as a food  preservative. Biotechnological approaches for its production using low-cost strategies are  recommended such as gene cloning strategy and genetic engineering.